1. Field of the Invention
The present invention relates to a high-speed printer such as an impact-type dot printer or a thermal printer used in a terminal device of a computer, or more particularly, to a dot printer provided with means for detecting abnormal printing caused by a break of print wires which are employed for dot print elements or by the deterioration of thermal printing elements or by trouble of the print drive circuit which drives these print elements.
2. Description of the Prior Art
Dot printer represents a character, figure or a symbol with dots in a matrix form such as 5.times.7 and has configurations such as an impact-type dot printer and a thermal printer and so on. In these printers, printing quality deteriorates due to the omission of dots which form a character when a defect such as a break of print wires occurs in dot print elements which are composed of print wires or thermal printing elements. When the number of omitted dots is one or two, the deterioration of printing quality is difficult to visually detect because of the normal blur of the ink or thermal sensitive materials on a print paper and the minimal deterioration. For that reason, an operater often does not become aware of the deterioration of printing quality for a long while when above-described defects occur in the dot print elements and, in extreme cases, the deterioration becomes such that mechanical reading by an optical character reader is impossible. In addition, printing quality deteriorates due to trouble in the print drive circuit.